The Simple Arithmetic of High Capacity Gun Magazines

In the wake of yet another mass shooting tragedy today, let’s examine the costs and benefits of high capacity gun magazines. I previously examined the cost-benefit of private gun ownership in the US, and noted at that time that the extraordinarily negative cost-benefit ratio might eventually become an issue for the pro-gun lobby (the industry generates economy-wide economic losses of over $15B/year) [1].

High capacity magazines [2] seem to have become a feature of virtually every recent mass-shooting in the US [3]. How many lives might have been saved by eliminating high-capacity magazines? Let us conservatively assume 10 deaths per year might be reduced through this policy (a rounding error compared to the roughly 10,000 annual gun homicides in the US). The economic value of 10 lives can be estimated at $80 million, while the annual sales revenue of high-capacity magazines might be less than $20 million (since gun magazine sales are a tiny fraction of gun sales, and magazines can be had for as little as $15) [4].

Measuring tragedy on an economic basis might seem crass, but it helps establish a key point: not only are high capacity magazines empowering individuals in mass shootings – but they are also provably hurting America as a whole, as they subtract value from our nation! An outright ban on possession of high capacity magazines is thus a reasonable step to limit further damage to America’s citizens and economy.

Let me address a number of potential criticisms here:

  • Would-be mass shooters will acquire weapons and high-capacity magazines illegally, so you are only affecting law abiding citizens. Actually, 75% of weapons used in mass shootings were acquired legally, and recent shooters acquired their weapons legally. Most of these shooters had no previous criminal record, so in the event high-capacity magazines were illegal, it’s unlikely that they would even know how to find them illegally.
  • Banning high-capacity magazines would have no effect on death rates, as shooters would simply reload. In the Gabrielle Giffords shooting, the gunman was stopped in his rampage once he stopped to reload. Reducing magazine capacity to 10 rounds reduces total firing capacity – this is simple arithmetic. In both of these shootings and many other incidents, lives would have been saved. For that matter, lives might be saved in incidents like drive-by shootings where the rapid fire of multiple rounds makes victims of innocent bystanders.
  • High capacity magazines are needed for self-defense. Even the police rarely find need to fire large numbers of rounds. Is there even one documented case of self defense where the potential victim needed more than 10 rounds to deter his attackers? There are outliers in everything, but I’d be surprised to hear of such a case.
  • I have a 2nd-Amendment right to whatever capacity magazine I like. The recent Supreme Court case upholding an individual right to a firearm also upheld the right to ban American citizens’ access to fully automatic weapons, grenades, tanks, and all other manner of military weapons. Even Justice Scalia admits that there are restrictions on the 2nd Amendment. Your right to purchase whatever weapon you like has long since been curtailed, and the government retains the right to enact reasonable restrictions on access to arms.


[1] Using more recent numbers on the economic value of human life at $8M per life, the gun industry may actually cause annual economic losses in the US of $200B per year (8M * 30k lives lost – economic value of gun trade). I republished the more conservative estimate above to remain consistent with the original analysis that I referenced.

[2] I am defining high-capacity magazines as those holding more than 10 rounds, as defined in the original assault weapons ban.

[3] Limiting gun capacity would have reduced casualties in a number of recent tragedies:

[4] Gun sales are estimated to have reached an annual rate around 12 million this year. If separate high-capacity magazine sales are in the neighborhood of 10% of all gun sales, and magazines cost around $15, then total annual revenue from this business might be 1.2M * 15 = $18M. This is an imprecise estimate, since gun sales are not tracked, but conveys the order of magnitude, and illustrates the tiny economic benefit supplied by this particular product relative to its cost in human life.

A trailer is not a gun show!

I grew up on a country road outside the small town of Leesville, LA. At the entrance to the road was a trailer where a friend of mine used to live. Some time after he moved away, the trailer became “Bunn & Sons Gun Shop,” with a red arrow painted to indicate the “gun show” around back. Why was a gun show in continuous operation behind a trailer on my road?

I didn’t know it at the time, but it turns out that the “gun show” was a response to the Brady Bill, enabling Bunn & Sons to use a loophole in the bill to sell handguns without a mandatory background check. Now, since this was the rural south, folks would always complain about how somebody was trying to take away their 2nd amendment rights. What is the actual text of the 2nd amendment?

A well regulated militia, being necessary to the security of a free state, the right of the people to keep and bear arms, shall not be infringed. – Bill of Rights, Amendment II

Reading these words, and interpreting them literally, it seems that the second amendment protects the right of the people to bear arms as part of a well-regulated militia. While the NRA would like to delete the first clause of the Amendment, it defines the right in the context of a militia, as noted in this summary at Thomson Findlaw.

The courts have clearly decided that the right to own a tank, rocket-propelled grenade launcher, or even a sawed-off shotgun is not necessarily protected under the 2nd Amendment. In the US v Miller, 1939, the Supreme Court Justice McReynolds wrote,

“In the absence of any evidence tending to show that possession or use of a ‘shotgun having a barrel of less than eighteen inches in length’ at this time has some reasonable relationship to the preservation or efficiency of a well regulated militia, we cannot say that the Second Amendment guarantees the right to keep and bear such an instrument.”

Federal firearms regulations also regulate the sale and transfer of firearms through the aforementioned Brady Bill and other legislation. Until recently, they also banned an entire class of semi-automatic weapons known as assault weapons.

Back to Bunn & Sons, and their “gun show”: all Bunn may have been trying to do was increase his business by removing the hurdle of an electronic background check from the sales process. In a larger context, the NRA has fought to keep the private-sale loophole available, in order to eliminate the background check process where possible. But why is the NRA so afraid of background checks? They argue that the overwhelming majority of American gun owners are law abiding citizens; then why not subject gun sales to the same level of scrutiny placed on prescription drug sales? For better or worse, guns are a part of American culture, and European-style gun restrictions will not and should not take place here. But with the advent of instant background checks, is it too much to ask that we control gun sales at least as much as we control sales of heart medication?